Picture-projecting apparatus.



c. E. CONVERSE E W. E10. RIDER.

PICTURE PROJECTING APPARATUS.

APPLIOAT1ON FILED MAR. 14, 1911. 1,062,081 Patented May 20, 1913.

mmm-mas FIG. 2:-

E Essas i n N.a

CHARLES E. CONVERSE AND WILLIAM H. C. RIDER, 0F CHICAGO, LLINOIS.

PICTURE-PROJECTING APPARATUS.

Specication of Letters Patent.

Patented May 20, i913.

To all w/lwm, t may concern:

Be it known that we, CHARLES H. CoN- vERsE and WILLIAM H. C. RIDER, bothcitizens of the United States, residing at Chicago, in the county ofCook and State of illinois, have invented a Certain new and usefulImprovement in Picture-Projecting Apparatus, of which the following is aspecification.

This invention relates to picture projecting apparatus, and moreparticularlyto apparatus for projecting moving pictures in which agelatin-coated Celluloid film is usually employed. This film is veryinfiammable, ordinarily igniting at a temperature of about 275 degreesF., and many disastrous fires have occurred from this cause.

One of the objects of our presentinvention is to provide an improvedheat arresting or protecting screen between the light and the film ofthe picture apparatus, for the purpose of defiecting or absorbing theheat rays, or a sufficient amount of the heat from the light, as toprevent the temperature of the'lm from rising to. a dangerous degree. Wehave discovered that by interposing a sheet or screen of Celluloidbetween the arc light of the apparatus and the film, certain heat rayswhich would otherwise affect the Celluloid film, are absorbed orarrested by the Celluloid screen, so that the film is protected andremains at a safe degree of temperature.

Another object is to provide an improved heat arresting and Colorscreen, through which the light may be projected to reproduce thepictures in various colors, tints, or shades, and according to thisfeature of our improvement, we employ colored Celluloid sheets, thecoloring being preferably applied as a coating of a gelatin .solution ofthe desired tint, shade, or Color.

ln the accompanying drawing: Figure 1 is a diagrammatic elevation of amoving picture apparatus, with our improvements applied thereto; Fig. 2,a side or edge view, showing one form of heat arresting screen` upon' alarger scale; Fig. 3, a front view of a slightly modified form ofscreen; and Fig. 4, a vertical section of the' same.

According to the construction shown, the picture projecting apparatuscomprises the usual lamp house B, containing arc llght A, condensinglens C, and shaping tube D, while G represents the kinetoscope or movingpicture machine, having film reels F,

for carrying the film K, and the projecting lens L, all of which may beof the ordinary well known construction. As the condensing lens C,concentrates the rays of light to meet substantially at the focal point,at which the moving picture film is exposed, with an area of less thanone square inch, it will be apparent that the heat rays will beconcentrated upon this small area and that the temperature willtherefore be very high at this point. In actual raCt-ice with the arclights, as ordinarily used). this temperature is found to beabout 320degrees F., or more, and as the ordinary Celluloid film ignites at alower degree of temperature, it follows that there is great danger ofthe film taking fire, if it should remain stationary and exposed to thislight for a short period of time, or even one or two seconds.

Various .attempts have been made to apply a fireproofing material to thefilm, and diierent ingredients have been employed, such ascellulousacetate, which is not as inflammable as the gelatin coatedCelluloid film, but it is liable to blister, and deteriorates rapidlyunder the high temperature v of the arc light of the machine.

According to one feature of our improvement, we interpose a sheet E, oftransparent Celluloid, cellulose, fibroid, or similar material,betweenthe lamp and the film, thus absorbing the -heat rays which affect suchcelluloid material, and rendering the use of the Celluloid or similarfilm perfectly safe. This sheet of Celluloid is preferably located nearthe point where the light emerges from the lens or shaping tube of thelamp house, at which point the circle of light is about three inches indiameter, covering an area of over siX square inches, or many timesgreater than that at which the moving picture film is exposed. As theheat rays are thus spread over such a large area of the'celluloidscreen, the temperature of the screen at no time rises to a dangerousdegree, even when exposed to the light Continuously, consequentlythereis no danger of the screen taking fire, and the film which may beof the usual gelatin coated Celluloid, or similar composition, is safelyprotected from the heat.

Either one or more sheets of the Celluloid material may be used, and ifdesired, the Celluloid sheet may bey coated with a gelatin emulsion orsolution, the principle of opera-` tion being that the Celluloid and thegelatin of the screen arrest and absorb the heat rays which affect thesematerials, so that tne film which is also composed of the same orsimilar materials is not materially affected in temperature as the lightpasses the film.

As will be readily understood by those familiar with the complex natureof light rays, certain specific heat rays which would affect thecelluloid materials in the lm may thus be absorbed or filtered out bythe interposed screen of similar celluloid materials, at the same timeallowing the free passage of all light rays and concomitant heat notaffecting such materials.

According to one construction, the celluloid screen E, may be composedof a plurality of thin sheets, of commercial celluloid, (either with orwithout the gelatin coating), rigidly connected together and separatedby thin air spaces O, open-at top and bottom, as shown more fully, inFig. 2. This circulation of air further tends to cool the 'sheets andthe use of a plurality of thin sheets offersless obstruction to thelight than a single thick sheet,

For the purpose of assisting in the radiation of the heat from thesurface of the celluloid sheets,`,'additional sheets of glass or similarmaterial may be inserted between the sheets of celluloid, and in contacttherewith. The glass may also serve to intercept some of the heat raysof the light,-but is mainly used to accelerate radiation andtransmission of heat from the sheets of celluloid material whichordinarily conduct heat rather slowly from one exposed surface toanother. Such a construction is illustrated'in Figs. 3 and 4, in whichalternate sheets of glass R, and the celluloid material E may be held inan aluminum casing S having openings T upon opposite sides for thepassage of the light. The casing may be provided with open spaces at topand bottom and also upon its side edges, if desired, i

combination with a lamp, and a film, of a to permit the circulation ofair through the spaces between the celluloid sheets.

It is understood that the terms celluloid and celluloid material, asherein used, are not limited to the' exact composition, but also includeAthe various similar substances of this class, such as cellulose,fibroid, commercial celluloid, etc., which are known to he .adapted foruse in the manufacture of films for picture projecting apparatus,

Any desired means may be employed for supporting the heat arrestingscreen in position, such as the clamp P, for attachment to the shapingtube D, as indicated diagrammatically in Figs. l and 2.

According to another feature of our improvement, we provide a series ofcolored celluloid screens H, any one or more of which may be interposedin the projected light between the lamp and the film, for the purpose ofprotecting the film, and giving any desired color, tint, or shade to thepicture. These screens may be colored by applying a coating of coloredgelatin solution to each sheetof celluloid, and the series of sheets maythen be adjustably supported in any suitable manner, so that any one ormore of the screens may be adjusted into or out of the light rays, asdesired.

Having now described our invention,what we claim as new, and desire tosecure by Letters Patent, is

l. In a picture projecting apparatus, the combination with the lamp, thecondensing lens, and the film, of a heat arresting celluloid screeninterposed between the lens and the film.

2. In a picture projecting apparatus, the combination with the'lamp, thecondensing lens and the lm, of a heat arresting celluloid sheet coatedwith a gelatinous solution 'interposed between the lens and the film.

3. In a picture projecting apparatus, the combination with a lamp, and ailm of celluloid material, of a heat-arresting screen of celluloidmaterial interposed between the lamp and the lm.

4. In a picture projecting apparatus, the

-combination with a lamp, and a ilm of inflammable material, of aheatresisting screen .composed of like material and interposed between thelamp and the film.

5. In a picture projecting apparatus, the

heat arresting screen composed of a plurality of sheets of celluloidmaterial spaced Qapart, and interposed between the lamp and

